Question 1

Which of the following best describes the process of wave (temporal) summation in skeletal muscle contraction?

Accepted Answer

Multiple stimuli are delivered before the muscle has completely relaxed, resulting in increased tension with each stimulus.

Question 2

During excitation-contraction coupling, which ion is released from the sarcoplasmic reticulum to initiate muscle contraction?

Accepted Answer

Ca$$^{2+}$$

Question 3

A muscle is stimulated with increasing frequency, and the contractions begin to fuse into a sustained contraction. What is this phenomenon called?

Accepted Answer

Complete (fused) tetanus

Question 4

Which of the following best explains the 'treppe' or 'warming up' effect observed in skeletal muscle?

Accepted Answer

Repeated stimulation of a rested muscle results in progressively stronger contractions due to increased Ca$$^{2+}$$ availability.

Question 5

Which type of muscle contraction occurs when the muscle shortens while generating tension?

Accepted Answer

Concentric contraction

Question 6

What is the primary role of acetylcholine (ACh) at the neuromuscular junction?

Accepted Answer

To bind to ligand-gated Na$$^{+}$$ channels, causing depolarization of the muscle fiber membrane.

Question 7

A subthreshold stimulus applied to a muscle fiber will result in which of the following?

Accepted Answer

No contraction will occur.

Question 8

Which statement best describes the force-velocity relationship in muscle contraction?

Accepted Answer

As the load opposing contraction increases, the velocity of muscle shortening decreases.

Question 9

During isometric muscle contraction, which of the following is true?

Accepted Answer

Muscle tension increases but there is no change in muscle length.

Question 10

Which of the following best describes motor unit recruitment in skeletal muscle?

Accepted Answer

Increasing the number of motor units activated increases the strength of muscle contraction.

Question 11

A patient receives a series of rapid stimuli to a muscle, resulting in a smooth, sustained contraction. Which equation best represents the relationship between frequency ($$f) $$and tension ($$T) in $$this scenario?

Accepted Answer

$$T \propto f$$

Question 12

Which of the following events occurs FIRST during excitation-contraction coupling?

Accepted Answer

Release of acetylcholine (ACh) from the motor neuron.

Question 13

Which of the following best explains why muscle can only pull and not push?

Accepted Answer

Muscle contraction shortens the muscle, generating tension that pulls on bones.

Question 14

Which of the following is TRUE regarding the effect of stimulus strength on muscle contraction?

Accepted Answer

A threshold stimulus is required to cause a contraction; subthreshold stimuli do not cause contraction.

Question 15

Which of the following best describes the role of voltage-gated Ca$$^{2+}$$ channels in the presynaptic neuron at the neuromuscular junction?

Accepted Answer

They allow Ca$$^{2+}$$ influx, triggering the release of acetylcholine (ACh) into the synaptic cleft.

Question 16

A muscle fiber is exposed to a single, brief stimulus. Which of the following best describes the resulting contraction?

Accepted Answer

A twitch

Question 17

Which of the following is the correct sequence of events in excitation-contraction coupling?

Accepted Answer

ACh release → Na$$^{+}$$ influx → depolarization → Ca$$^{2+}$$ release → contraction

Question 18

Which of the following best describes an eccentric muscle contraction?

Accepted Answer

The muscle lengthens while generating tension.

Question 19

If a muscle is stimulated at a frequency that allows partial relaxation between contractions, what type of contraction is produced?

Accepted Answer

Incomplete (unfused) tetanus

Muscle Contraction: Physiology, Summation, and Force Generation

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